西北地区混凝土修补用聚合物砂浆试验研究

发布时间：2018-12-31 19:27

【摘要】：西北干寒地区的混凝土常年受到冻融循环、盐碱腐蚀、风蚀等多种自然因素的作用,日积月累,极易在混凝土结构中产生裂缝、剥蚀等病害。混凝土裂缝等病害如不及时修复,会加速混凝土结构的劣化,严重降低混凝土结构的耐久性,进而影响其安全服役。因此,研究如何修补产生裂缝等病害的混凝土,以及用什么材料修补具有重要的工程意义。本文针对西北干寒、盐碱和风蚀等自然环境,研究了适合于该地区混凝土病害的修补用聚合物砂浆。本文研究了乳化沥青、CR乳液和丙烯酸乳液改性聚合物砂浆的拌制、养护、工作性能、粘结性能和力学性能,分析了乳化沥青、CR乳液和丙烯酸乳液加入量对聚合物改性砂浆含气量、凝结时间、流动性、粘结性和力学性能的影响,对比分析不同改性乳液对各项指标的影响。从最后的研究成果来看,与普通砂浆相比,聚合物改性砂浆的抗折强度和抗压强度均略有下降,随着聚合物乳液掺量的增加强度先增大后减小,最佳掺量为15%左右;聚合物乳液和掺合料的掺入使砂浆在西北地区的条件下亦能获得较好的内部孔结构和较高的力学强度,这表明改性砂浆比普通砂浆更适合于条件复杂的现场施工;聚合物乳液可以起到减水的效果。稠度固定时,水灰比例会逐渐减小,水泥水化过程和速度依旧没有飞速加快,而是根据聚合物掺量比例的加大,初凝时间和终凝时间按照先降低后升高的曲线发展规律,但从凝结时间曲线来分析,聚合物并没有加速凝结作用,在聚合物添加很多的情况下才具有较强的缓凝作用。氯丁胶乳的掺入大大提高了砂浆的抗压强度,28d龄期时相对纯砂浆增加2.7%。丙烯酸乳液的掺入对砂浆的抗折强度的提高显著。28d龄期聚合物掺量为20%时,抗折强度影响最大,比纯砂浆要高3.6%。90d时抗压强度相对纯砂浆提高了9%。聚合物改性砂浆的折压比与龄期的关系呈反比。即龄期是增大聚合物改性砂减小,主要是由于砂浆的抗压强度比抗折强度同期增加幅度要大。砂浆的粘结强度与掺量含量成正比,掺入量增加而粘结强度增长。对粘结强度的影响最为显著的当属氯丁胶乳,90d时粘结强度提高了20%。但丙烯酸在同一龄期时则降低了聚合物改性砂浆的粘结强度。主要原因是由于丙烯酸掺入量过多。它的量比在砂浆中没有促进形成网状的聚合物膜的效果,相反还减缓了水泥的水化过程。通过试验数据可以推算出最佳养护环境并对养护条件的匹配性机理进行分析。
[Abstract]:The concrete in the dry and cold area of northwest China is affected by many natural factors such as freeze-thaw cycle, salt alkali corrosion, wind erosion and so on. It is easy to produce cracks and denudation in concrete structure. If concrete cracks and other diseases are not repaired in time, the deterioration of concrete structures will be accelerated, the durability of concrete structures will be seriously reduced, and the safety of concrete structures will be affected. Therefore, it is of great engineering significance to study how to repair concrete with cracks and other diseases and what materials to repair. In this paper, polymer mortar suitable for repairing concrete diseases in Northwest China is studied, which is suitable for repairing concrete diseases in northwest China, such as dry cold, salt alkali and wind erosion. In this paper, the mixing, curing, working properties, bond properties and mechanical properties of emulsified asphalt, CR emulsion and acrylic emulsion modified polymer mortar are studied. The effects of the amount of CR emulsion and acrylic emulsion on the air content, setting time, fluidity, adhesion and mechanical properties of polymer modified mortar were compared and analyzed. Compared with ordinary mortar, the flexural strength and compressive strength of polymer modified mortar decreased slightly. With the increase of polymer emulsion content, the flexural strength and compressive strength of polymer modified mortar increased first and then decreased, and the optimum content was about 15%. The addition of polymer emulsion and admixture makes the mortar obtain better internal pore structure and higher mechanical strength under the condition of northwest China, which indicates that the modified mortar is more suitable for the field construction with complex conditions than ordinary mortar. Polymer emulsion can reduce water. When the consistency is fixed, the water-cement ratio will gradually decrease, and the hydration process and speed of cement will not accelerate rapidly, but according to the increase of polymer content ratio, the initial setting time and the final setting time develop according to the curve of decreasing first and then increasing. However, according to the setting time curve, the polymer does not accelerate the condensation, and it has a strong retarding effect only when the polymer is added a lot. The compressive strength of mortar was greatly increased with the addition of Chloroprene latex, and the relative pure mortar increased by 2.7% at 28d age. The flexural strength of mortar increased significantly with the addition of acrylic acid emulsion. When the polymer content of 28 days was 20, the flexural strength of mortar was the greatest, and the compressive strength was increased by 9% compared with pure mortar at 3.60.90 d than that of pure mortar. The relationship between the flexural pressure ratio and the age of polymer modified mortar is inversely proportional. The main reason is that the compressive strength of mortar is larger than that of flexural strength. The bond strength of mortar is in direct proportion to the content of mortar. The most significant effect on the bond strength was Chloroprene latex, which increased the bond strength by 20 times after 90 days. However, acrylic acid decreased the bond strength of polymer modified mortar at the same age. The main reason is the excessive incorporation of acrylic acid. The ratio does not promote the formation of the polymer membrane in mortar, on the contrary, it slows down the hydration process of cement. The optimum curing environment can be deduced from the test data and the matching mechanism of the curing conditions can be analyzed.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU578.1

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